Lubricating greases containing an acidic copolymer salt



United States Patent LUBRICATING GREASES CONTAINING AN ACIDIC COPOLYMER SALT John J. Giammaria, Woodbury, N. J., assignor to Socony- Vacuum Oil Company, Incorporated, a corporation of New York No Drawing. Application March 15, 1951,

Serial No. 215,859

9 Claims. (Cl. 252-39) The present invention relates to lubricating greases and, more particularly, to lubricating greases containing metal salts of co-polymers of alpha, beta unsaturated polycarboxylic acids or their anhydrides with aliphatic compounds having a terminal vinyl group, -CH=CH2.

Heretofore, the most generally used gelling agents for preparing lubricating greases have been soaps of fatty acids such as stearic, palmitic, oleic acids, and more recently the salts of the hydroxy fatty acids such as the hydroxystearic acids. Greases have also been made using mixtures of various soaps including mixtures of fatty acid soaps and hydroxyfatty acid soaps. More recently, such materials as carbon black, silica flour and alkyl ammonium bentonite have been claimed as gelling agents.

This new class of gelling agents comprises metal salts of acidic copolymers such as are formed by reacting long chain aliphatic compounds containing a terminal vinyl group, CH=CH2, with an alpha, beta unsaturated polycarboxyl'ic acid or anhydride in the presence of an organic peroxide catalyst.

The vinyl compounds which can be used to form the t acidic copolymers with the alpha, beta unsaturated polycarboxy-lic acids are aliphatic alpha olefins, allyl esters of aliphatic acids, allyl ethers of aliphatic alcohols, vinyl esters of aliphatic acids and vinyl ethers of aliphatic alcohols. The alpha olefins, RCH=CH2, and allyl esters, RCOOCH2CH=CH2 in both of which R is an alkyl radical having at least 10 and up to carbon atoms, preferably 10 to 22 carbon atoms and especially a mixture averaging about 18 carbon atoms are especially suitable for the preparation of the copolymers per se, the metal salts of which are the subject of the present invention. Such compounds are further preferred since they are readily available, of relatively low cost, and tend to form lower molecular weight copolymers, the latter being an important factor in the preparation of suitable gelling agents. Of particular interest for economic reason-s are the alpha olefins l-dodecene, l-hexadecene, l-octadecene and higher alpha olefins and mixtures thereof such as are obtained by thermal cracking of petroleum wax or waxy petroleum stocks or fractions. Illustrative of the allyl esters are allyl laurate, allyl myristate, allyl palmitate, allyl stearate, mixed allyl esters such as are obtained by esterifying allyl alcohol with hydrogenated fish fatty acids which contain aliphatic monocarboxylic acids having 10 to 22 carbon atoms, and in general allyl esters obtained by esterifying allyl alcohol with an aliphatic monocarboxylic acid having 10 to 22 carbon atoms. It is not necessary that single acids be used for mixtures of saturated and unsaturated monooarboxylic acids can be used to prepare the allyl esters. Illustrative of such a mixture is a mixture of stearic and oleic acids or stearic and the linseed oil acids.

0f the alpha, beta unsaturated aliphatic polycarboxylic acids the dicarboxylic acids are preferred. Illustrative of the preferred dicarboxylic acids are maleic, fumaric, itaconic, gluta-conic, mesaconic and oitraconic, and the tricarboxylic aconitic acid. Of these maleic acid in the form of its anhydride is preferred at this time because of its ready availability, cost and because it is highly reactive. It will be recognized by those skilled in the art that the anhydrides of the acids or the acid halides as well as the acids having less than 10 carbon atoms per se can be used although generally it is preferred to use the anhydrides in the preparation of the copolymers. The allyl ethers can be either the allyl ethers of monoice Q hydric or polyhydric alcohols although the ethers of monohydric alcohols are preferred. The preparation of these ethers is well known merely involving the reaction between an allyl halide and the sodium alcoholate. Thus, for example, allyl methyl ether, methallyl butyl ether,- allyl amyl ether, allyl heptyl ether, methallyl octyl ether, allyl lauryl ether, allyl hexadecyl ether, methallyl octadecyl ether and the like can be used.

Suitable catalysts for the copolymerization of an aliphatic compound having a terminal vinyl group,

and an alpha, beta unsaturated aliphatic polycarb'oxylic' acid, especially a dicarboxylic acid, are the organic peroxides such as benzoyl peroxide, di-tertiary-butyl perox ide, and lauroyl peroxides and the hydroperoxides, such as cumene hydroperoxide. These latter catalysts are somewhat less effective than the peroxides as catalysts in this reaction.

The copolymerization of the aliphatic compound having a terminal vinyl group, hereinafter designated a vinyl compound, with an alpha, beta unsaturated aliphatic polycarboxylic acid or anhydride is accomplished by heating substantially equi-molar quantities of the reactants at temperatures within the range of about 75 C. to about C. in the presence of about 0.1 to about 5.0 per cent of peroxide catalyst. The amount of peroxide catalyst required varies with the type of vinyl compound used. Thus, for example, with a vinyl ester or vinyl ether, 0.5 to 1.0 per cent of peroxide catalyst is sufficient while about 2.0 to about 3.0 per cent of peroxide catalyst is required with an alpha olefin or an allyl ester. The copolymerization can be carried out in the presence or absence of a solvent. Suitable solvents are toluene, xylene, dioxane, highly acid-refined mineral oil such as white oil and the like. For the purpose of commercial grease-making, the vinyl compound and the alpha, beta unsaturated polycarboxylic acid can be copolymerized in a suitable pressure kettle and the viscous copolymer diluted with hot mineral oil of the required viscosity at the completion of the reaction.

As has been stated herein'before, the novel gelation agents of the present invention are metal salts of the aforeenumerated copolymers. Suitable metals for the preparation of these gelling agents are the members of groups I to IV of the periodic system. In general, salts of the metals of groups I, II and III of the periodic sys: tem, including lithium, calcium, barium and aluminum salts are preferred. Any of the standard methods for the preparation of salts of organic acids can be used. For example, the copolymer either in the anhydride form or after hydrolyzing to the free acid form in any suitable manner as with boiling water, can be neutralized with the hydroxide or alcoholate of the metal desired or the alkali metal or ammonium salt of the acidic copolymer can be reacted with the chloride, hydroxide, carbonate or other salt of the metal the copolymer salt of which is required. As a general, but by no means sole, Procedure, about 10 to about 25 per cent of the acidic copolymer is blended in a mineral oil of suitable viscosity, the amount of metal hydroxide or oxide required to neutralize all of the carboxyl groups of the copolymer is added to the blend and the mixture heated, while agitating, from about 300 to about 500 F. The mixture is held in this temperature range, for about 0.5 to about 3 hours. The resulting grease is cooled with or without agitation in the grease kettle or drawn off into pans to cool.

Since the metal salts which are the present novel gela- -tion agents are prepared from acidic copolymers whose structure has been acceptably established, the structure of the novel gelation agents can be postulated therefrom. In an article, The Peroxide-induced Copolymerization of Allyl Acetate with Maleic Anhydride, P. D. Bartlett and K. Nozaki, J. A. C. S, vol. 68, pp. 14954504 (1946), the probable structure of the 1:1 copolymer of an aliphatic compound having a terminal vinyl group with an alpha, beta unsaturated aliphatic polycar'boxylic acid, is represented by the following formula when the polycarboxylic acid is a dicarboxylic acid in the anhydride [I I 1 J CH2 H H t n.

where B. is the alkyl residue of an olefin, an allyl ester or an allyl ether, i. e., R is R-, RQ and RCOO. and R is an alkyl group.

It has been found that the value of n in the formula given hereinbefore for the acidic copolymer preferably should be 3 to 4. That is, the average molecular weight of the acidic copolymers from which the present gelation agents are prepared preferably is about 1000 to about 2000.

In the light of the foregoing it is manifest that the salts of the acidic copolymers will have obvious but various structures dependent (1) upon the valence of the metal of the salt. po he pre ence of m re th n on acidic component in the reaction mixture durrrrg the formation of the salt and (3) upon the presence and valence of more than one metal in the reaction mixture during the formation of the salt. Thus, when making the salt of a monovalent metal and a mixture of acidic copolymers, the resulting gelation agent will be a mixture of monovalent metal salts of the various acidic copolymers. Such a mixture can contain for example the following salts:

- OM 0 0M- where M is the same or different monovalent metal of group I of the periodic system. Of course, it is obvious that when polyvalent metals of groups I to IV of the periodic system are used the resulting gelation agents are more complex since there can be cross-linking of acidic copolymer units through the polyvalent metal as well as simple neutralization of, say, two carboxylic groups of the same copolymer unit by one atom of divalent metal. The probable structures of the components of a gelation agent prepared from a trivalent metal such as aluminum are manifest. Therefore, it will be understood that the present gelation agents can be of simple components or a plurality of components dependent upon the presence l) of one or more metals of single valence, (2) of one or more acidic copolymers, (3) of a polyvalent metal and one or more acidic copolymers or (4) of a plurality of monoand polyvalent metals and a plurality of acidic copolymers.

Thus, greases containing, for example, a lithium-barium salt of an acidic copolymer, or a lithium salt of one acidic copolymer and a barium salt of another acidic copolymer can be prepared.

The copolymer metal salts can be used alone as gelation agents or in combination with other gelation agents such as soaps of conventional fatty or hydroxy fatty acids, carbon black, silica flour and the like.

For example, it has been found that greases having a very smooth texture can be prepared by converting a mixture of an acidic copolymer and a fatty acid to metal salts in the oleagenous vehicle. Mixtures containing about per cent to about 90 per cent of fatty acid and about 90 per cent to about 10 per cent (by weight) of oil-free acidic copolymers can be used to produce the salts which are novel gelation agents. However, it is preferred to use about equal parts by weight of an acidic copolymer having a molecular weight of about 1000 to about 2000 and a straight-chain, saturated fatty acid. The fatty acids suitable for this purpose are the individual fatty acid or mixtures of fatty acids or hydroxy fatty acids having 10 to 22 carbon atoms in the molecule such as capric, lauric, stearic, hydroxy-stearic acid and hydrogenated fish oil fatty acids. The acidic copolymer and fatty acid are reacted with a single metal compound or a plurality of compounds of a plurality of metals of groups I to IV of the periodic system. Furthermore, the mineral oil vehicle can be replaced wholly or in part by synthetic oils of the polyester, polyether and silicone types. Thus, for example, the mineral oil vehicle can be replaced wholly or in part by an aleagenous vehicle, for example, an estcr type syntheticoil such as 2-ethylhexyl sebacate or by a polyether synthetic oil such as polyalkylcne glycol or by a silicone such as methyl polysiloxane or by a polymer oil obtained by polymerization of an olefin such as ethylene.

e foregoing cu s n h ndica h pe of the present invention but it is believed unnecessary to illustrate each combination and permutation within the scope thereof. The following illustrative but non-limiting examples of some specific combinations are illustrative of the general procedure for preparing the acidic copolymers, the salts thereof and the greases therefrom.

While the preparation of acidic copolymers of an allyl ester of a fatty acid and an alpha, beta unsaturated aliphatic polycarboxylic acid anhydride is known, the following examples of the preparation of such copolymers are illustrative of the general methods.

PREPARATION OF COPOLYMERS Example A (allyl ester-allyl stearate; alpha, beta unsaturated polycarboxylic acid anhydride-mulch: anhydride) A mixture of about 314 parts by weight of allyl stearate (about 0.969 mole), about 94.8 parts by weight of maleic anhydride (about 0.966 mole), about 8.0 parts by weight of benzoyl peroxide (about 1.95 weight per cent), and about 88 parts by weight of xylene (as a diluent) was gradually heated in a container equipped with a stirrer, a condenser and a thermometer. At about to about C. a strongly exothermic reaction occurred, causing a rapid temperature rise to about 160 C. The viscous reaction mixture was substantially stripped of solventdiluent xylene and the crude copolymer cooled to about 100 C. The copolymer was then diluted with about 1.0 volume of A. S. T. M. naphtha and cooled to ambient temperatures, 15 to 25 C. The solution was filtered and the naphtha topped off. A resinous copolymer was obtained in a yield of about 93 per cent of theoretical. The neutralization number (milligrams per gram of copolymer) by potentiometric titration was 193.0.

A mixture of about 322 parts by weight of allyl stearatc (about 0.996 mole) and about 98 parts by weight of maleic anhydride (about 1 mole) was dissolved in about 260 parts by weight of toluene (as a diluent) and the solution was heated to about 100 C. About 12.6 parts by weight (3 weight per cent) of benzoyl peroxide were added in small portions over a period of about one hour, allowing the rate of addition of the peroxide to maintain a temperature about 100 to about C. When the addition of the peroxide was completed, the solvent was topped off the reaction mixture by raising the temperature thereof to about C. The viscous copolymer remaining as a still residue was dissolved in about 1230 parts by weight of an acid-treated nap'nthenic oil having an S. U. V. 100 F. of seconds to give a blend of about 25 per cent of copolymer in oil. The neutralization number of the oil blend (milligrams KOH per gram of blend) was found by potcntiometric titration to be 61.0.

A mixture of about 314 parts by weight of allyl stearate (about 0.969 mole), about 94.8 parts by weight of nlalcic anhydride (about 0.966 mole) and about 8.0 parts by weight (about 1.95 weight per cent) of benzoyl peroxide was gradually heated in a grease kettle. Exothermic reactron occurred at 100-l05 C. causing a rapid temperature rise to about C. The copolymer was blended in the kettle with an acid-treated, naphthenicoil having an S. U. V. 100 F. of 232 seconds to provide a blend amazes containing about 25 weight percent of copolymer having a neutralization "number (milligrams "KOH per" gram of blend) of 53.0.

D Preparation of copolymer ,(allyl stearate-allyl oleatemaleic 'anhydride) A mixture of about 322 parts by weight of 75,per cent allyl stearate and 25 per cent allyl oleate and about '98 parts by weight of maleic anhydride was dissolved in about 260 parts by weight of toluene; The solution was heated to about 100 C. and about.12.6 parts by weight (about 3 weight per cent) of benzoyl peroxide were added in small portions during a period of about one hour, allowing the rate of addition of benzoyl peroxide to maintain a temperature of about 100 to about 110 C. After the addition of the peroxide was completed, the toluene was topped off by raising the temperature of the mixture to about 150 C. The viscous copolymer which was obtained as a still residue was dissolved in about 1230 parts by weight of an acid-treated, naphthenic oil to provide a blend containing approxirnately 25 weight per cent of the copolymer. The blend so obtained had a neutralization number of 56.0.; E

*Preparation of copolymer (allyl laurate-maleic anhy- 1 dride) A copolymer of allyl laurate and maleic anhydride was prepared in a manner similar to that described in B, supra, ablend of this copolymer in a naphthenic oil having an S. U. V. at 100 F. of 232 seconds and containing about 25 weight per cent of the copolymer had a neutralization number of 73.0. t p F Preparation of copolymer (octadecene-maleic anhydride) A mixture of about 125 parts by weight of l-octadecene, about 49 parts by weight of maleic anhydride, about 3.5 parts by Weight of benzoyl peroxide and about 265 parts by weight of xylene was gradually heated to about 140 C. The solution was then cooled to about 70 C. and an additional 1.7 parts by weight of benzoyl peroxide were added. Thereafter the solution was heated to about 140 C. and then to about 200 C. at a pressure of about 5 millimeters of mercury to distill xylene and unreacted materials. A yellow resinous copolymer was obtained in about 90 per cent yield. The neutralization number by potentiometric titration was 187.0.

An acidic copolymer of maleic anhydride and the allyl ester of hydrogenated fish oil fatty acids was prepared in the manner described under Preparation of Copolymers-B. The acidic copolymer thus obtained was blended with a quantity of solvent-refined naphthenic oil having an S. U. V. 100 F. of 513.5 seconds to provide a blend containing weight per cent of the acidic copolymer. This blend had a neutralization number of 57.0.

PREPARATION OF GREASE Example I (lithium grease) A grease was prepared by mixing 4.5 parts by weight of the copolymer (Preparation A), 25.5 parts by weight of an acid-treated, naphthenic oil having an S. U. V. 100 F. of 232 seconds and a viscosity index of 43.0, 0.63 parts by weight of lithium hydroxide (LiOH-lIzO) and 3 parts by weight of water, and heating the mixture to about 400 F. with stirring. Samples were removed at intervals to observe the degree of gelation. Heating of the mixture was continued at about 400 F. to about 420 F. for about 1 hour. The mass was then cooled while stirring. Although the grease was quite soft at room temperature, it set to a still, buttery consistency during the next few days.

Example 11 (barium grease) A mixture of about 4.5 parts by weight of copolymer with stirring. A thick gel formed at about 200 F. and.

about 12.5 partsby weight of the same naphthenic oil Example III (barium grease) About 500 partsby weight of the copolymer blend (Preparation B)... about 400 parts of naphthenic oil havng an S. U. V. F of 232 seconds, and a viscosity index of 43.0 and about 95 parts by weight of barium hydroxlde (Ba(OH)z-8H2O) were heated in a suitable grease kettle. A thickgel formed atabout 175 F. which became more fluid at about 220 F. The mass started to thicken at about ,250",F. and was ,quite, viscous at about 350 F. The mass'became progressively thicker while heating for about 45 minutes at about 350 F. and then became more fluid and less dry in appearance. Thickening again occurred after about 10 minutes. Heating was continued at about 350 F. for about 1.5 hours but no further change was observed. The grease was cooled to about F. whilst stirring the mass and then to ambient temperatures. At ambient temperatures (about 75 F.) the grease showed good mechanical stability and no tendency to bleed.

Example IV (calcium grease) About 225 parts by weight of copolymer blend (Preparation B), about 180 parts by weight of a solvent-refined naphthenic oil having an S. U. V. 100 F. of 513.5 seconds and a viscosity index of 60.5, 12.5 parts by weight of calcium hydroxide (Ca(OH)2) and about 2 parts by weight of water were charged to a suitable grease kettle. The mixture was heated to about 350 F. during a period of about 1.5 hours but remained fluid throughout. It was then cooled to about 180 F. and about 5 parts by weight of water added and reheated. A thick gel formed at about 220 F. which became more fluid at 240 F. and quite fluidat 320 F. At about 350 F. the mass became thicker and continued to thicken while it was heated at about 350 to about 360F. for about 0.5 hour. No further change was observed after about 0.25 hour additional heating at about 350 to about 360 F. and the grease was cooled to about F. while stirring the mixture. At ambient temperatures the grease showed good mechanical stability and no tendency to bleed.

Example V (lithium grease) About 320 parts by weight of a 25 per cent copolymer blend (prepared as in B) having a neutralization number of 58.0, about 200 parts by weight of a naphthenic oil having an S. U. V. at 100 F. of 232 seconds and a viscosity index of 43.0, about 14.2 parts by weight of lithium hydroxide (Li(OH)-H2O) and about 10 parts- Example VI (aluminum grease) A mixture of about 200 parts by weight of the copolymer blend (Preparation C) having a neutralization number of 53.0 and about 200 parts by weight of an acidtreated, naphthenic oil having an S. U. V. at 100 F. of 232 seconds and a viscosity index of 43.0 was charged to a grease kettle and heated. At about 150 F. 12.9 parts by weight of aluminum isopropoxide were added. Heating .of the mixture was continued to about 250 F. at which temperature a gel was formed. The temperature of the mass was raised to about 325 F. and held at that temperature for about 1.5 hours. The mass was cooled toambienttemperatures without agitation. The mass wasthen worked to a smooth, clear, grease of good me:

chariical stability.

7 Example VII (aluminum grease) A mixture of about 200 parts by weight of the copolymer blend (Preparation C) and about 200 parts by weight of an acid-treated, naphthenic oil having an S. U. V. at 100 F. of 232 seconds and a viscosity index of 43.0 was charged to a grease kettle and heated to about 400 F. At this temperature the mass was quite fluid. The mass was cooled to ambient temperatures without agitation and then was worked to a smooth, clear, grease similar to that obtained as described in VI.

Example VIII (Calcium grease) In a manner similar to that described in Example IV, a grease containing about 18 weight per cent of a calcium salt of the aforedescribed copolymer (Preparation D) was prepared.

Example IX (Zinc grease) About 300 parts by weight of allyl stearate-maleic anhydride copolymer (Preparation C), about 200 parts by weight of an acid-treated naphthenic oil having an S. U. V. 100 F. of 232 seconds, about 33 parts by weight of zinc acetate (Zn(OOCCH3)z-2H2O) and about parts by weight of water were gradually heated to about 260 F. at which temperature a soft, heterogeneous gel was formed. The gel became thicker and more homogeneous at about 280 F. and was quite homogeneous at about 350 F. The temperature of the mass was raised to about 375 F. but no further change was observed. The mass was cooled to ambient temperatures with stirring.

Example X (Barium grease) A barium grease was prepared from the aforesaid allyl laurate-maleic anhydride copolymer (Preparation E) in a manner similar to that described in III supra. The grease so obtained contained about 18.5 weight per cent of the barium salt of the allyl laurate-maleic acid anhydride copolymer.

Example XI (Calcium grease of acidic copolymer and saturated fatty acid) A mixture of 200 parts by weight of acidic copolymer blend (Preparation G), 50 parts by weight of stearic acid, 20 parts by weight of calcium hydroxide [Ca(OI-I)2], parts by weight of water and 350 parts by weight of a solvent-refined naphthenic oil having an S. U. V. 100 F. of 513.5 seconds was heated in a suitable grease kettle. A smooth gel was formed at about 200 F. which became more fluid at about 250 F. and thickened again at about 270 F. A thick, heterogenous gel was formed at about 285 F. which became dry and hard at about 305 F. At about 330 F. it became softer and smoother and remained soft and smooth while being heated to about 375 F. The grease was then cooled to ambient temperature (about 75 F.) while stirring. The resulting grease was very smooth in texture and showed good mechanical stability and no tendency to bleed.

Example XII A portion of the grease prepared as Example XI was reheated to about 375 F. with stirring. It was then cooled statically to ambient temperature. This grease was heavier in consistency than that prepared in Example XI and also showed good mechanical stability and no tendency to bleed.

Example XIII (Barium grease) About 50 parts by weight of the l-octadecene-maleic anhydride copolymer (Preparation F), about 300 parts by weight of an acid-treated naphthenic oil having an S. U. V. at 100 F. of 232 seconds and about 29 parts by weight of barium hydroxide (Ba(OH)2-8H2O); (about 10 per cent in excess of the equivalent based upon the neutralization number of the copolymer) were heated to about 360 F. during about 1.5 hours. No gelation occurred. The fluid mass was cooled to about 175 F. and about 10 parts by weight of water added and the mixture reheated. The mass became thick and foamed at about 250 F. At about 300 F. the foaming had subsided and a smooth, homogeneous gel was formed which become thicker at about 315 F. No further change was observed upon heating to about 350 F. The resultant grease was cooled to about 150 F. with stirring. Thereafter the grease was cooled to ambient 8 temperatures at which temperatures the grease was quite stiff, showed good mechanical stability and no tendency to bleed.

Greases such as those described hereinbefore and others containing metal salts of acidic copolymers of an aliphatic compound having a terminal vinyl group and an alpha, beta unsaturated polycarboxylic acid anhydride have been tested and found to possess a high degree of mechanical stability, water resistance and oxidation stability. The data in Table I are indicative of the character of these greases. In addition various of these greases have been subjected to a ball and roller-bearing test for hours at 200 F. and have shown no Wear or leakage from the bearing.

As those skilled in the art will understand the greases contemplated by the present invention can contain in addition to the salt of the copolymer or copolymers, additives such as adhesiveness or string-imparting agents, for example rubber latex, polysiobutylene, acrylic ester polymers; extreme pressure agents, for example, sulfurized sperm oil; oxidation inhibitors, such as phenyl alpha naphthylamine; inorganic fillers, for example, carbon black, silica flour; and the like.

The greases of the present invention can contain an amount of copolymer salt between about 5 weight per cent and 50 weight per cent depending upon the consistency desired or required. The oil employed can be naphthenic, paraflinic or mixed base having an S. U. V. at 100 F. of about 100 to about 600 seconds or higher depending upon the application of the grease. Of course, those skilled in the art will understand that the viscosity and type of oil employed will regulate the amount of copolymer salt employed within the limits given hereinbefore. However, copolymer salt concentrations of about 5 to about 25 per cent generally are suitable for the preparation of greases for most uses.

I claim:

1. A grease comprising a mineral lubricating oil fraction and a salt in an amount suflicient to thicken said oil fraction to form a grease, said salt being a salt of an acidic copolymer of an aliphatic compound having a terminal vinyl group and an alkyl radical having from ten to thirty carbon atoms and an alpha, beta unsaturated polycarboxylic acid, the metal of said salt being selected from the group consisting of metals of groups I, II and III of the periodic system, and said acidic copolymer having a molecular weight of about 1000 to about 2000.

2. A grease as defined by claim 1 wherein the polycarboxylic acid is in the form of its corresponding anhydride and is maleic anhydride.

3. A grease as defined by claim 1 wherein the aliphatic compound contains from ten to eighteen carbon atoms in the molecule, and wherein the polycarboxylic acid is in the form of its corresponding anhydride and is maleic anhydride.

4. A grease comprising a mineral lubricating oil fraction, a salt (1) of a fatty acid having ten to twenty-two carbon atoms in the molecule and a salt (2) in an amount suificient to thicken said oil fraction to form a grease, said salt (2) being a salt of an acidic copolymer of an aliphatic compound having a terminal vinyl group and an alkyl radical having from ten to thirty carbon atoms and an alpha, beta unsaturated polycarboxylic acid, the metal of said salt (2) being selected from the group consisting of metals of groups I, II and III of the periodic system, and said acidic copolymer having a molecular weight of about 1000 to about 2000.

5. A grease comprising a mineral lubricating oil fraction, a salt (1) of stearic acid and a salt (2) in an amount sufiicient to thicken said oil fraction to form a grease, said salt (2) being a salt of an acidic copolymer of the allyl ester of hydrogenated fish oil fatty acids and maleic anhydride, said acidic copolymer having a molecular weight of about 1000 to about 2000; the metal of said salts 1) and (2) being selected from the group consisting of metals of groups I, II and III of the periodic system; and the amount of said salt (1) being approximately equal to the amount of said salt (2).

6. A grease comprising an oleaginous vehicle and a salt in an amount suflicient to thicken said vehicle to form a grease, said salt being a salt of an acidic copolymer of an aliphatic compound having a terminal vinyl group and an alkyl radical having from ten to thirty carbon atoms and an alpha, beta unsaturated polycarboxylic acid having not more than ten carbon atoms in the molecule, the metal of said salt being selected from the group consisting of metals of groups I, II and III of the periodic system, and said acidic copolymer having a molecular weight of about 1000 to about 2000.

7. A grease comprising a mineral lubricating oil fractiori and a salt in an amount sufficient to thicken said oil fraction to form a grease, said salt being a salt of calcium and of an acidic copolymer having a molecular Weight of about 1000 to about 2000 of maleic anhydride and of an allyl ester of a monocarboxylic acid, said acid having twelve to twenty-two carbon atoms in the molecule.

8. A method of preparing a grease, which comprises: mixing an oleaginous vehicle with a salt in an amount to thicken said oil fraction to form a grease, said salt being a salt of an acidic copolymer of an aliphatic compound having a terminal vinyl group and an alkyl radical having from ten to thirty carbon atoms and an alpha, beta unsaturated polycarboxylic acid, the metal of said salt being selected from the group consisting of metals of groups I, II and III of the periodic system, and said acidic copolymer having a molecular weight of about 1000 to about 2000; and maintaining the mixture thus formed at labout 300 F. to about 500 F. for at least about one our.

9. A method of preparing a grease which comprises: mixing an oleaginous vehicle, an acidic copolymer of an aliphatic compound having a terminal vinyl group and an alkyl radical having from ten to thirty carbon atoms and an alpha, beta unsaturated polycarboxylic acid, and said acidic copolymer having a molecular weight of about 1000 to about 2000, and an amount of a metal compound selected from the group consisting of an oxide, a hydroxide and a carbonate, the metal of which is selected from the group consisting of a metal of groups I, II and III of the periodic system, slightly in excess of that required to neutralize said acidic copolymer; holding said mixture at about 200 F. until the formation of a salt of said metal and said acidic copolymer is substantially complete; holding the resulting mixture at about 300 F. to about 500 F. for at least one hour; and cooling the resulting product to ambient temperature; the amount of said salt present in the product being suflicient to thicken said oil fraction to form a grease.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 22,299 Earle Apr. 13, 1943 1,976,679 Fikentscher et al Oct. 9, 1934 2,197,263 Carmichael et al Apr. 16, 1940 2,384,595 Blair Sept. 11, 1945 2,460,035 Rogers et a1 Jan. 25, 1949 2,483,959 Baer Oct. 4, 1949 2,483,960 Baer Oct. 4, 1949 2,491,028 Beerbower Dec. 13, 1949 2,497,432 Blake Feb. 14, 1950 2,513,680 Shott et al. July 4, 1950 2,533,376 Jones Dec. 12, 1950 2,542,542 Lippincott et al Feb. 20, 1951 2,543,964 Giammaria Mar. 6, 1951 2,565,981 Morway Aug. 28, 1951 2,570,788 Giamrnaria Oct. 9, 1951 2,577,706 Hotten Dec. 4, 1951 2,615,845 Lippincott et al. Oct. 28, 1952 2,615,864 Giammaria Oct. 28, 1952 2,616,849 Giammaria Nov. 4, 1952 2,634,256 Sparks et al Apr. 7, 1953 2,637,698 Tutwiler May 5, 1953 

1. A GREASE COMPRISING A MINERAL LUBRICATING OIL FRACTION AND A SALT IN AN AMOUNT SUFFICIENT TO THICKEN SAID OIL FRACTION TO FORM A GREASE, SAID SALT BEING A SALT OF AN ACIDIC COPOLYMER OF AN ALIPHATIC COMPOUND HAVING A TERMINAL VINYL GROUP AND AN ALKYL RADICAL HAVING FROM TEN TO THIRTY CARBON ATOMS AND AN ALPHA, BETA UNSATURATED POLYCARBOXYLIC ACID, THE METAL OF SAID SALT BEING SELECTED FROM THE GROUP CONSISTING OF METALS OF GROUPS I, II AND III OF THE PERIODIC SYSTEM, AND SAID ACIDIC COPOLYMER HAVING A MOLEJCULAR WEIGHT OF ABOUT 1000 TO ABOUT
 2000. 